Field of the Invention
The present invention relates to a perpendicular magnetic recording medium. Particularly, the present invention relates to a perpendicular magnetic recording medium having a magnetic layer comprising an ordered alloy, comprising Fe and Pt as components, and further comprising vanadium (V).
Description of the Related Art
Recently, higher density magnetic recording is in high demand. As a technology for realizing the high density of the magnetic recording, a perpendicular magnetic recording method is employed. The perpendicular magnetic recording medium includes at least a non-magnetic substrate and a magnetic recording layer formed of a hard magnetic material. The perpendicular magnetic recording medium may further include a soft magnetic under layer which plays a role of concentrating a magnetic flux generated by a magnetic head to the magnetic recording layer, an interlayer for orienting the hard magnetic material of the magnetic recording layer in an intended direction, a protective film for protecting a surface of the magnetic recording layer and the like arbitrarily and selectively.
For the purpose of obtaining favorable magnetic characteristics, formation of a magnetic recording layer of the perpendicular magnetic recording medium by using a granular magnetic material has been proposed. The granular magnetic material comprises magnetic crystal grains and a non-magnetic segregant surrounding a periphery of the magnetic crystal grains. The individual magnetic crystal grains in the granular magnetic material are magnetically separated by the non-magnetic segregant.
Moreover, as the metal magnetic material for a perpendicular magnetic recording medium, a CoCr-based disordered alloy magnetic layer including CoCrPt has been mainly studied. Recently, for the purpose of further improvement of recording density of the perpendicular magnetic recording medium, it is imminent to reduce a grain size of the magnetic crystal grain in the magnetic layer. Here, the reduction of the grain size of the magnetic crystal grain lowers thermal stability of recorded magnetization. Thus, in order to compensate for the lowering of thermal stability caused by reduction of the grain size of the magnetic crystal grain, use of a material with higher crystal magnetic anisotropy is in demand.
As the material having the higher crystal magnetic anisotropy in demand, an L10-ordered alloy and its manufacturing method are proposed. The L10-ordered alloy includes FePt, CoPt, FePd, CoPd, and the like.
With the ordered alloys as above, it is difficult to obtain better crystal grains with higher order parameter. Moreover, in the granular magnetic materials, separability of the individual magnetic crystal grains in the granular magnetic material needs to be improved so as to realize better crystallinity with higher order parameter.
Japanese Patent Laid-Open No. 2003-313659 discloses a sputter target for forming a thin film of an L10-ordered alloy. As this sputter target, an FePtV-based alloy having a composition of Fe≤Pt is described as an example in Japanese Patent Laid-Open No. 2003-313659. In Japanese Patent Laid-Open No. 2003-313659, an ordered alloy film having a high magnetic anisotropy constant (Ku), a high coercive force (Hc), and the like, can be obtained with good reproducibility by lowering an anneal temperature when a magnetic alloy film formed by sputter film deposition is ordered in an L10-ordered phase. Moreover, in Japanese Patent Laid-Open No. 2003-313659, the magnetic recording medium enables regularization of the magnetic alloy film to an L10-ordered phase at a relatively low anneal temperature and thus, practical utility and mass productivity of the magnetic recording medium using the ordered-phase alloy film with the L10-structure having a large magnetic anisotropy constant (Ku) as a recording layer are improved.
Japanese Patent Laid-Open No. 2008-059733 discloses a magnetic recording medium comprising an alloy having a high magnetic anisotropy constant (Ku) and an oxide compound, and a sputter target for forming a magnetic recording layer of such a magnetic recording medium. Japanese Patent Laid-Open No. 2008-059733 discloses that, since the magnetic recording layer has the high magnetic anisotropy constant (Ku), thermal stability is improved, and a magnetic domain of this magnetic recording layer can be made extremely small. Moreover, as the sputter target in Japanese Patent Laid-Open No. 2008-059733 for forming a thin film of the L10-ordered alloy, an FePtV oxide-based alloy is described as an example.